Skin barrier function is essential for skin health and protects against chemical and biological insults from the outside environment. Skin attenuates the penetration of harmful radiation, including ultraviolet (UV) radiation, into deeper skin layers and prevents infection. Skin also acts as a permeability barrier and prevents loss of body moisture. Dysfunction of the skin barrier can lead to chronic skin conditions, disease, and in extreme cases, can even threaten the viability of the organism.
Topical compositions comprising extracts from bacteria have been described (see U.S. Patent Publication Nos. 20140335137 and 20140186433). For example, extracts of Micrococcus luteus comprising endonuclease, a DNA repair enzyme, have been used in compositions for sun-damaged skin. To prepare such compositions, cells are lysed to release the intracellular endonuclease, which is collected from the lysate and added to the composition. Lysis of the cells can be achieved using a number of methods, including the use of heat, chemicals (e.g., acid/base), enzymes (e.g., lysins, proteases, amylases), ultrasound, physical stress (e.g., pressure, homogenization, mechanical disruption; freeze/thaw cycling), radiation (e.g., gamma, ultraviolet), osmotic shock, viral infection, lytic gene expression, and others known in the art. Such methods for lysing cells cleave the bacterial cell wall and degrade the basic cell structure. The lysed cell wall and other structural components are typically separated from the endonuclease-containing portion of the lysate and discarded. Topical compositions comprising live Micrococcus luteus have also been described (see U.S. Patent Publication No. 20110189133). The live Micrococcus luteus cultures can compete with other skin flora to treat or prevent skin disorders associated with unwanted bacterial growth. However, delivery of live organisms to the skin can be challenging from a formulation and safety standpoint, especially in compromised skin.
Inflammation and its associated disruption of homeostasis can decrease skin barrier function. During an inflammatory response, cells of the immune system (e.g., lymphocytes and macrophages) and skin cells (e.g., Langerhans cells and keratinocytes) release cytokines, which can be pro-inflammatory (e.g., interleukin (IL)-1, IL-1α, IL-1β, IL-8, IL-12, IL-18, and TNF) or anti-inflammatory (e.g., IL-4, IL-1 receptor antagonist (IL-1Ra or IL-1RN, IL-10, IL-11, and IL-13). Compositions and methods for regulating cytokine production to treat and prevent inflammation provide a beneficial impact on skin barrier function and overall skin health and are continuing objectives in the personal care and cosmetic industry.